The purpose of this study is to rigorously test the efficacy of a couples-based HIV and sexually transmitted infection (HIV/STI) preventive intervention for African American/Black men who have sex with men (MSM) in same sex intimate relationships in which at least one partner is using stimulants (herein referred to as stimulant-using, African American MSM couples). The proposed study is a logical progression from the investigative team's prior formative research to take an existing couples based intervention originally for heterosexual couples (Connect) and revise/tailor it for methamphetamine-using, African American MSM couples. The adapted intervention was pilot tested using a pre-/post-test design. Findings revealed statistically and clinically significant reductions in sexual and drug risk behaviors. In addition, this formative research informs the proposed study in several additional ways: (1) the importance of addressing stimulants beyond methamphetamine with African American MSM; (2) qualitative data on how a couples-based intervention can interrupt relationship dynamics more unique to drug-involved, African American MSM couples that lead to risk behavior; and (3) couples-based HIV prevention research is feasible, promising, and safe for stimulant using, African American MSM. This earlier research has culminated with a 7-session, manualized intervention entitled Connect 'n Unite (or CNU-pronounced seein' you-for short) as a candidate couples-based HIV preventive intervention for stimulant-using, African American MSM couples. The proposed study is a randomized clinical trial with 270 stimulant-using, African American MSM couples to test the impact of CNU versus a wellness promotion (WP) attention control condition on behavioral and biologically assayed outcomes over a 12-month follow-up period. The study has the following primary aims: (1) to test whether participants assigned to CNU engage in lower HIV/STI behavioral risk-fewer number of unprotected acts of anal intercourse, greater proportion of protected acts of anal intercourse, and fewer number of sexual partners-compared to participants assigned to WP; (2) to test whether participants assigned to CNU have lower cumulative incidence of STIs-chlamydia and gonorrhea-confirmed via biological assay compared to participants assigned to WP; and (3) to test whether participants assigned to CNU engage in less drug use and drug-related HIV risk (i.e., sex under the influence of drugs/alcohol) compared to participants assigned to WP. If successful, this study will advance the field by providing an evidence-based, innovative intervention that can be delivered in drug treatment and other service settings to reduce the spread of HIV among stimulant-using, African American MSM.